51781919 has 8 divisors (see below), whose sum is σ = 59243520. Its totient is φ = 44336376.

The previous prime is 51781913. The next prime is 51781927. The reversal of 51781919 is 91918715.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 51781919 - 2¹² = 51777823 is a prime.

It is a super-2 number, since 2×51781919² = 5362734270645122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51781913) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3962 + ... + 10920.

It is an arithmetic number, because the mean of its divisors is an integer number (7405440).

Almost surely, 2^51781919 is an apocalyptic number.

51781919 is a deficient number, since it is larger than the sum of its proper divisors (7461601).

51781919 is a wasteful number, since it uses less digits than its factorization.

51781919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8029.

The product of its digits is 22680, while the sum is 41.

The square root of 51781919 is about 7195.9654668432. The cubic root of 51781919 is about 372.7285962295.

The spelling of 51781919 in words is "fifty-one million, seven hundred eighty-one thousand, nine hundred nineteen".